The disclosed embodiments of the present invention relate to mixing audio inputs, and more particularly, to an audio mixing method and audio mixing apparatus capable of processing and/or mixing audio inputs individually.
When there are multiple audio inputs, an audio mixing operation may be performed for mixing the audio inputs to generate a mixed audio output for following audio playback. Taking a Blu-ray disc (BD) playback system for example, a BD disc may provide a plurality of audio inputs, such as a primary audio bitstream, a secondary audio bitstream, and an effect sound data which may be a pulse-code modulation (PCM) stream, when loaded into a BD player and accessed by the BD player. Besides, the BD player has multiple audio output interfaces, such as an analog interface (i.e., L/R RCA jacks) and a high-definition multimedia interface (HDMI). Generally, the multiple audio output interfaces are required to provide multiple audio outputs simultaneously. In a conventional design of the BD player, the effect sound data (i.e., a PCM stream) is mixed with the primary audio bitstream and/or the secondary audio bitstream, and then the mixed result is post-processed to generate the required audio outputs to the audio output interfaces.
The conventional design of the BD player has many drawbacks. For example, when the effect sound data corresponds to a mono channel, the mono effect sound should be preferably mixed to a center channel if the center channel exists. Consider a case where the analog interface of the BD player is a stereo audio interface. If the effect sound mixing is performed by referring to the channel configuration supported by the analog interface of the BD player, the effect sound is mixed to a left channel and a right channel. However, when the HDMI interface of the BD player is connected to a speaker system supporting multi-channel playback (e.g., a 5.1-channel speaker system), no effect sound is played via a center-channel speaker due to the fact that the effect sound is mixed to the left channel and the right channel rather than the center channel. As a result, a user who has the 5.1-channel speaker system fails to have the best listening experience of the effect sound playback. Besides, as the post-processing is performed after all of the available audio inputs are mixed, there is no option allowed to post-process the audio inputs individually.